Stability is the biggest thing that bags provide. If bags are used for extra load rating then the truck is not big enough.
Bags can also bounce more so good shocks are a must.
I have them on my 3500 DRW and I really like the stability they add.

fixx
 

and dont be cheap when buying the bags,,get the set with a air gauge in the cab to monitor the air pressure..if you loose the air in them which they all leak it will distroy the bags,,you need to keep a minimum of 10 psi in them or they will rupture..

I love my firestone bags, have over half million miles on A set! Zero problems. I also overload them everyday.

X2 I love the Firestones on my Avalanche 2500. What it did is smooth out the ride while towing the Chris Cat on Michigans lousy roads..

I've had them installed on all 4 of my trucks since I've been towing boats. They are fantastic for controlling squat, sway, and overall truck/trailer handling.

I think it's night and day difference. I've installed them on all my tow vehicles sure makes it nice to level out a truck when needed.

+ 1 had them on my f-250 when I towed heavy loads they really made a difference and it was sweet to be able to level rear end squat.

anybody on half tons